Advanced Imaging Magazine

Stereopsis: Two Eyes, One 3D Image

Planar Systems, Inc.

Planar's StereoMirror monitor consists of two active matrix LCD (AMLCD) units oriented at a 110-degree angle and bisected by a passive beamsplitter mirror. When stereo pair images from the two monitors are viewed through crossed-polarizing the result is a single, fused stereoscopic image.

In a standard 2D screening, the radiologist must correlate the three-dimensional structure within the breast from the two orthogonal (right-angle) views. Subtle lesions are difficult to detect because of overlying and underlying normal tissue that can mask it. A stereoscopic digital mammogram consists of two x-ray images of the breast acquired from slightly different points of view on a digital mammography unit. The x-ray source is rotated 10 degrees between the two exposures. Then the stereo pair of mammograms is viewed on a high-resolution stereo display.

The mammographer views the display wearing polarized glasses, enabling him or her to see in depth the internal structure within the breast. As a result, a subtle lesion that may be obscured by superimposed normal tissue in a standard 2D image, now becomes visible as the overlying and underlying normal tissue is separated in depth. Conversely, layers of tissue that may falsely resemble a lesion in a standard 2D image due to chance imposition are seen in the stereo mammogram at different depths and will not be mistaken for a lesion. Although a final report has not been issued, indications are strong that false negatives and false positives are both reduced when 3D viewing is employed.

A study at the University of Pittsburgh is investigating increases in productivity and sensitivity in lung cancer diagnoses through stereo 3D visualization of CT chest images. It, too, is showing early indications of more efficiency.

We all know that in minimally invasive surgery recovery time is shortened and quality of recovery is improved. The surgeon uses an endoscopic or laparoscopic fiber optic probe that relays images to a monitor. A stereo view helps the surgeon's depth perception, making the operation even safer. Say, for example, the surgeon is working on the pericardium, the sac that surrounds the heart. The doctor wants to see and understand exactly where he is cutting. Stereo gives him or her an enhanced tool.

Diabetes is an insidious disease. One of its many serious side effects is diabetic retinopathy, hemorrhaging of the retina. The depth of the retina is 2mm at its thinnest point. With a 3D view, doctors see the hemorrhage between the artery and the vein as little dots and can go in and cauterize the bleeding.